scholarly journals Synthesis, Optimization, Property, Characterization, and Application of Dialdehyde Cross-Linking Guar Gum

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Tang Hongbo ◽  
Li Yanping ◽  
Zhang Wen ◽  
Dong Siqing
Keyword(s):  
Thermal Stability ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Guar Gum ◽  
Sodium Periodate ◽  
Decomposition Temperature ◽  
Melting Enthalpy ◽  
Cross Linking ◽  
The Cross ◽  
Thermal Stability Of

Dialdehyde cross-linking guar gum (DCLGG), as a novel material, was synthesized using phosphorus oxychloride as a cross-linking reagent, sodium periodate as an oxidant, and ethanol as a solvent through keeping the original particle form of guar gum. The process parameters such as the reaction temperature, reaction time, pH, amount of sodium periodate, and amount of ethanol were optimized by the response surface methodology in order to obtain the regression model of the oxidization. The covalent binding of L-asparagine onto the surfaces of DCLGG was further investigated. The results showed that the best technological conditions for preparing DCLGG were as follows: reaction temperature = 40°C, reaction time = 3.0 h, pH = 4.0, and amount of ethanol = 74.5%. The swelling power of DCLGG was intermediate between cross-linking guar gum and dialdehyde guar gum. The cross-linking and dialdehyde oxidization reduced the viscosity of GG. The cross-liking reduced the melting enthalpy of GG. However, the oxidization increased melting enthalpy of ACLGG. The thermal stability of GG was increased by cross-linking or oxidization. The variation of the onset decomposition temperature and end decomposition temperature of GG was not consistent with thermal stability of GG. L-asparagine could be chemically bound well by DCLGG through forming Schiff base under the weak acidity. The maximum adsorption capacity of L-asparagine on DCLGG with aldehyde content of 56.2% reached 21.9 mg/g.

Properties of Polyaniline with the Doping of Different Acid

2012 ◽  
Vol 502 ◽  
pp. 31-35 ◽  
Author(s):  
Xiao Hua Wang
Keyword(s):  
Thermal Stability ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Acid Content ◽  
In Situ Polymerization ◽  
Ammonium Persulfate ◽  
Dodecylbenzenesulfonic Acid ◽  
Thermal Stability Of

Polyaniline(PANI) with the doping of hydrochloride(HC1), aminosulfonic acid (NH2SO3H) or dodecylbenzenesulfonic acid(DBSA) was prepared by in-situ polymerization. Effects of acid content, reaction time, oxidant ammonium persulfate (APS) dosage and reaction temperature on the conductivity of PANI were studied. The resistance and thermal stability of them were compared. Results show that the largest conductivity of HC1-PANI is 1.98 s.cm-1 among them in case the C(HC1)=0.5mol/L, reaction time is 6.0h, n(APS/aniline)=1.0; The conductivity of NH2SO3H-PANI is 0.2s.cm-1 in case the C(NH2SO3H)=1.0mol/L, reaction time is 6.0h, n(APS/aniline)=2.0; The conductivity of DBSA-PANI is 0.98s.cm-1 in case the C(DBSA)=1.0 mol/L, reaction time is 8.0h, n(APS/aniline) = 2.0. The the least resistance of HC1-PANI is 10Ω, and that of NH2SO3H- PANI is the largest of 120Ω. The order of their thermal stability is DBSA-PANI > NH2SO3H-PANI > HC1-PANI before 350°C, that of their thermal stability is inverse when it reaches 350°C.

Characterization of Thermal Reversible Cross-Linking Agents for Flexible Poly(vinyl chloride)

2014 ◽  
Vol 900 ◽  
pp. 3-6 ◽  
Author(s):  
Jing Wang ◽  
Wei Fang ◽  
Yuan Yuan ◽  
Xiao Ming Liu
Keyword(s):  
Thermal Stability ◽  
Vinyl Chloride ◽  
Congo Red ◽  
Cross Linking ◽  
Gel Content ◽  
Ethyl Mercaptan ◽  
Poly Vinyl Chloride ◽  
The Cross ◽  
Thermal Stability Of

In order to improve thermal stability of Poly (Vinyl Chloride), a kind of thermal reversible cross-linking agents, the end cyclopentadienyl ethanethiol salts, sodium cyclopentadienyl ethyl mercaptan (CPD-C2H4SNa) was synthesized in this paper. The DSC results proved that the prepared CPD-C2H4SNa has obvious thermal reversible characteristics and the thermal reversible temperature was at 177 °C. The effects of cross-linking agent amount, cross-linking reactive time and temperature on flexible PVC compounds were evaluated through gel content testing. It was showed that the cross-linking agent with 3 Phr is optimum for PVC compounds. Moreover, both the cross-linking reactive time and temperature has effects on gel content of PVC compounds. The gel content of CPD-C2H4SNa cross-linked PVC compounds reaches maximum at 76% for 20 min at 160 °C.The static thermal stability of flexible PVC was measured according to congo red method. The results showed that the thermal stability of PVC compounds was enhanced with increasing cross-linking agent amount.

THERMOREVERSIBLE COVALENT CROSS-LINKING OF MALEIC ANHYDRIDE GRAFTED BUTYL RUBBER WITH GLYCEROL

2015 ◽  
Vol 88 (3) ◽  
pp. 373-389 ◽  
Author(s):  
Lin Li ◽  
Shuai Zhao ◽  
Zhenguo Ma ◽  
Zhenxiang Xin
Keyword(s):  
Reaction Time ◽  
Maleic Anhydride ◽  
Reaction Temperature ◽  
Butyl Rubber ◽  
Cross Linking ◽  
Molar Ratios ◽  
Cross Links ◽  
The Cross ◽  
The Fourier Transform ◽  
Percentage Conversion

ABSTRACT The formation of thermoreversible hemi-ester cross-links of maleic anhydride grafted butyl rubber (MAn-g-IIR) using glycerol as a cross-linking agent in the absence of catalyst was studied in the present work. The effects of the molar ratios of glycerol to anhydride, the amount of the mixed solvent, the reaction temperature, and the reaction time on the percentage conversion of anhydride to ester were determined. The maximum percentage conversion calculated from the Fourier transform infrared spectroscopy spectra was 52.11. Reaction temperature played the most important role on the percentage conversion, followed by reaction time. Compared with the original MAn-g-IIR, tensile strength of the hemi-ester cross-linked MAn-g-IIR was significantly improved. These macromolecular regular clusters acted as strong and multiple cross-linking points that led to impressive mechanical properties. This confirmed the formation of hemi-ester cross-links. The covalently cross-linked MAn-g-IIR was reprocessable via compression molding at 179 °C and higher, indicating that the cross-links were indeed thermoreversible. The cross-linked materials could be repeatedly compression molded at 179 °C into homogeneous films for at least three cycles.

scholarly journals Bio-Based Thermo-Reversible Aliphatic Polycarbonate Network

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 74 ◽  
Author(s):  
Pierre-Luc Durand ◽  
Etienne Grau ◽  
Henri Cramail
Keyword(s):  
Thermal Stability ◽  
Biomedical Applications ◽  
Diels Alder ◽  
Cross Linking ◽  
Important Class ◽  
Aliphatic Polycarbonate ◽  
Biomedical Field ◽  
The Cross ◽  
Thermal Stability Of

Aliphatic polycarbonates represent an important class of materials with notable applications in the biomedical field. In this work, low Tg furan-functionalized bio-based aliphatic polycarbonates were cross-linked thanks to the Diels–Alder (DA) reaction with a bis-maleimide as the cross-linking agent. The thermo-reversible DA reaction allowed for the preparation of reversible cross-linked polycarbonate materials with tuneable properties as a function of the pendent furan content that was grafted on the polycarbonate backbone. The possibility to decrosslink the network around 70 °C could be an advantage for biomedical applications, despite the rather poor thermal stability of the furan-functionalized cross-linked polycarbonates.

Cross-linking of atoms and thermal stability of new MDF compositions

1996 ◽  
Vol 46 (2) ◽  
pp. 479-487 ◽  
Author(s):  
M. Drábik ◽  
Lubica Gáliková ◽  
Zuzana Sadleková ◽  
Mária Kubranová
Keyword(s):  
Thermal Stability ◽  
Cross Linking ◽  
Thermal Stability Of

scholarly journals Effect of Nanodiamond Particles on Properties of Epoxy Composites

2008 ◽  
Vol 17 (1) ◽  
pp. 096369350801700 ◽  
Author(s):  
Zdeno Špitalský ◽  
Alexander Kromka ◽  
Libor Matějka ◽  
Peter Černoch ◽  
Jana Kovářová ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Epoxy Composites ◽  
Neat Epoxy ◽  
Light Transmittance ◽  
Cross Linking ◽  
Amino Groups ◽  
Multiwalled Carbon ◽  
Epoxy Network ◽  
Epoxy Nanocomposite ◽  
Thermal Stability Of

The epoxy nanocomposites filled with 0.1, 0.5, and 1 wt% nanodiamonds (nanoD) were prepared and their properties were compared with neat epoxy network or epoxy nanocomposite filled with 1 wt% multiwalled carbon nanotubes (MWCNTs). The obtained nanoD-epoxy composites increased significantly thermal stability of prepared nanocomposites in comparison with neat epoxy matrix. The exponential decay of light transmittance with increasing concentration of nanoD in sample was observed. The values of storage modulus G` and glass transition temperature Tg significantly decreased by addition of nanoD to epoxy network. This is caused by inhibition of cross-linking reaction of epoxy- and amino- groups by nanoD.

scholarly journals The Thermal Properties of Polyurethane/Neoprene Blends on Prosthetic Foot

2020 ◽  
Vol 990 ◽  
pp. 106-110
Author(s):  
Mohd Zulkifli Mohamad Noor ◽  
Mohamad Anas Mohd Azmi ◽  
Mohd Shaiful Zaidi Mad Desa ◽  
Mohd Bijarimi Mat Piah ◽  
Azizan Ramli
Keyword(s):  
Thermal Stability ◽  
Thermal Properties ◽  
Low Cost ◽  
Decomposition Temperature ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Prosthetic Foot ◽  
Reinforced Polymer ◽  
New Material ◽  
Thermal Stability Of

Neoprene reinforced polymer has become an attraction in current research and development of new material blend. In this invention, neoprene was chosen to be enhance to polyurethane because of their superior properties that possess extraordinary mechanical, electrical, optical and thermal properties on prosthetic foot. In this research, polyurethane was chosen due to good rigidity, easy processing and low cost. The reinforcement polyurethane with neoprene is expected to improve the properties of polyurethane. The objective of this research was conducted to investigate the effect of neoprene contents on thermal properties of polyurethane reinforced neoprene on prosthetic foot. The effect of neoprene on thermal properties neoprene reinforced polyurethane was analysed in term of its thermal stability by thermal gravimetric analysis (TGA). Moreover, the visual of small topographic details on the surface of polyurethane/neoprene blends will be examined by scanning electron microscope (SEM). Based on result, the thermal properties show the great enhancement at high neoprene contents which is 1.0wt%. The thermal stability of polyurethane reinforced neoprene improves when the temperature where decomposition starts to occurs are higher than decomposition temperature of pure polyurethane. Then, thermal conductivity of polyurethane shows the great improvement after the addition of neoprene. Lastly, the smooth surface and visible of sheets pattern on surface represent the present of neoprene disperse into polymer that enhance brittleness. Thus, the presence of neoprene has clearly enhanced the thermal stability of the polyurethane. Table 1 shows formulation of neoprene and polyurethane.

Influence of the Precursor Cross-Linking Route on the Thermal Stability of Si−B−C−O Ceramics

2008 ◽  
Vol 20 (22) ◽  
pp. 7148-7156 ◽  
Author(s):  
Vladislav Ischenko ◽  
Eckhard Pippel ◽  
Jörg Woltersdorf ◽  
B. Rodrigue Ngoumeni Yappi ◽  
Ralf Hauser ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Cross Linking ◽  
Thermal Stability Of

Studies on Thermal Stability and Rheological Property of PU/PVDF Blend

2011 ◽  
Vol 311-313 ◽  
pp. 1065-1070
Author(s):  
Guo Lan Huan ◽  
Jian Li Liu ◽  
Qi Yun Du ◽  
Xiao Yu Hu
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Thermal Decomposition ◽  
Shear Stress ◽  
Rheological Property ◽  
Decomposition Temperature ◽  
Dynamic Equations ◽  
Thermal Decomposition Temperature ◽  
Thermal Stability Of ◽  
Decomposition Activation Energy

In this article, the thermal stability of PU/PVDF blend was investigated by thermogravimetry (TG), and their rheological property was studied through testing and analyzing the rheological curves. The results showed that, with the increase in PVDF content, the thermal decomposition temperature of PU/PVDF blend increased, and by fitting relevant data to thermal decomposition dynamic equations, it was found that thermal decomposition activation energy of the blend increased gradually, i.e. the thermal stability of the blend increased gradually. Meantime, based on the curves of shear stress vs. shear rate of the blend at 180°C and 200°C, it was shown that for PU/PVDF blend, with the decrease of temperature and the increase in PVDF content, the non-Newtonian index decreased, while the viscosity of the blend increased.

scholarly journals A Long-Chain Alkylation of Dialdehyde Starch to Improve Its Thermal Stability and Hydrophobicity

2016 ◽  
Vol 2016 ◽  
pp. 1-7
Author(s):  
Jiang Zhu ◽  
Zhaodong Wang ◽  
Haitao Ni ◽  
Xiang Liu ◽  
Jian Ma ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Orthogonal Experiment ◽  
Raw Material ◽  
Molar Ratio ◽  
Dialdehyde Starch ◽  
Hydrophobic Properties ◽  
Feed Composition ◽  
Long Chain

Hydrophobic dialdehyde starch (HDAS) was synthesized by dialdehyde starch (DAS) and eighteen-alkyl primary amine as the raw material in DMSO. The effect of the reaction conditions on the yield of HDAS was investigated such as catalyst content, reaction temperature, reaction time, and the in-feed molar ratio of -CHO/-NH2. Moreover, the optimized test parameters were obtained by conducting orthogonal experiment. The molecular structure and the morphology of HDAS were characterized via Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). And the thermal stability and the hydrophobic properties of HDAS were investigated by thermal gravimetric analyzer (TG) and the hydrophobic testing. The results indicate that the yield of HDAS is the highest up to 44.21%, with feed composition 1 : 0.9, reaction temperature 40°C, reaction time 8 h, and acetic acid content 3%. And the introduction of the long-chain alkyl groups into the DAS backbones will ameliorate efficaciously the thermal stability and the hydrophobic properties of DAS, which almost has no effect on the DAS particle size.

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